I entered a home with corona virus and did not get infected? i have a very strong immune system? Is it common to not. tested day 7. negative?

you might have a good immune system, i dont get it either when ive been around people that have had it

There are many reasons that some people get covid and others don't.

Age is definitely a factor - this is an adult illness.  The older the more likely to acquire covid, worse infections, and more deaths.

People with Type O blood are less likely to get covid.

People with adequate levels of vitamin D have a 54% chance of not getting covid.

And then there is the meaning of your statement... "entering" is not going to cause a covid infection.  You need to have "close contact" with an infected individual.

In response to the comment:

Close contact is defined as being within 6ft for more than 15minutes in a 24hour period.

= if you just gave them a hug, you aren't a close contact.  If you sat and chit chatted you could be.  But if they were asymptomatic at testing, the virus might not have been active enough to cause infection when you were nearby. 

Probably just luck or maybe your a carrier that won't get it but will put others in the hospital. 

FWIW, there's an 80% chance that the person who tested positive with Covid-19 never had it in the first place.

Up to 80% of the positive results are FALSE POSITIVES. 

Why do you think those 80% only have flu-like symptoms?

Because they have the flu.